On April 3, 2025, the “Decree amending and supplementing various provisions of the Regulatory Law of Sections I and II of Article 105 of the Political Constitution of the United Mexican States” (the “Decree”) was published in the Official Gazette of the Federation (by its Spanish acronym “DOF”). The Decree modifies key provisions governing actions of unconstitutionality and constitutional controversies filed before the Supreme Court of Justice of the Nation (by its Spanish acronym “SCJN”).
The following are some of the most relevant points of the Decree:
1. Lowering of the voting threshold for declaring invalidity and general effects. In line with the constitutional reform of the Federal Judiciary published in the DOF on September 15, 2024, the Decree provides that rulings declaring the invalidity of general norms and those producing general effects will now require six (6) votes instead of eight (8). This amendment will take effect upon the swearing-in of the new justices, scheduled for September 1, 2025, pursuant to the three transitory articles of the Decree.
2. Exclusion of constitutional amendments from judicial review. A new Section VIII Bis is added to Article 19, establishing as a ground for inadmissibility any constitutional controversy seeking to challenge amendments or additions to the Federal Constitution, thereby limiting the scope of concentrated constitutional review exercised by the Supreme Court.
3. Priority handling of matters involving social interest or vulnerable groups. The Decree adds a provision allowing the Chief Justice of the SCJN to submit to the Plenary a proposal for priority resolution of certain cases, when requested by either Chamber of Congress or by the Federal Executive, particularly in matters involving the rights of vulnerable groups or issues of public interest.
4. Normative update and inclusive language. The Law is updated to reflect the elimination of the Chambers of the SCJN, the implementation of electronic means, the use of digital signatures, the adoption of inclusive language, and the application of the Unit of Measure and Update (UMA) as the reference for sanctions.
5. Strengthening the role of the reporting justice. The powers of the instructing justice are expanded, who may now conduct hearings, receive evidence, issue procedural warnings, and prepare draft rulings with broader discretion, including the authority to summarily dismiss claims or conduct incidental matters through oral hearings.
6. Clarification of representation and procedural rules. The Decree clarifies the rules for legal representation of the parties, particularly for the President of the Republic, Congress, and other public entities; it also defines procedural deadlines, notification methods, and rules of evidence.
The foregoing shows that the reform seeks to modernize the Regulatory Law of Article 105 in line with the new institutional framework of the Federal Judiciary. However, some of the changes introduced have raised concerns, particularly with regard to the exclusion of constitutional amendments from judicial review, which may weaken the system of checks and balances within the Mexican constitutional framework.
The reduction of the voting threshold, combined with the centralization of powers in the Chief Justice and the strengthening of the instructing justice’s role, could diminish the traditionally collegial and deliberative nature of the Court’s Plenary. Rather than improving efficiency, these changes may result in more centralized decision-making, potentially affecting the internal balance and democratic legitimacy of constitutional adjudication.
In this context, the practical implementation of the Decree should be carefully monitored by legal practitioners to assess whether these modifications enhance the constitutional justice model or, on the contrary, undermine its ability to safeguard constitutional supremacy in the face of potential abuses of power.
